Bacterial Motility-From Physics To Human Health

Evolving on planet Earth for billions of years, microbes have developed an ability to move in liquid or on moist surfaces. Flagellated bacteria can swim in water with the aid of helical shaped flagella. Each flagellum is driven by a rotary motor embedded at the bacterial cell wall. Besides swimming, many species of bacteria also display swarming motility, an impressive form of collective migration as a growing population of bacteria spreads over moist surfaces. The fundamental fluid mechanics and interfacial physics account for a rich variety of patterns expanding bacterial colonies develop, including fingerlike protrusions (Yang 2017), expanding wavefronts (Du 2012), and dynamic droplets (Ma 2021). Our ongoing study focuses on a particular species of bacteria, the Enterobacter sp. SM3, which is identified from murine hosts under conditions relevant to the human inflammable bowel disease (IBD). SM3 manifests strong swarming behavior, whereas its isogenic mutants isolated from healthy control animals do not swarm as strongly (De 2021). It is hoped that the study of swarming motility of SM3 may reveal its hidden benefit on disease amelioration. More broadly, new knowledge of bacterial swarming motility might lead to biomedical and environmental applications.